Fuel pump governor



` Sept. 3, 1946. V uR, J, lFlELD 2,AQ7,013

FUEL APUMP GOVERNOR Filed Nov. 15, 1944 Patented Sept. 3, 1946 RichardJoseph rItielda Ealing, London, England, assigner .to Joseph LucasLiitjd, Birmingham',

England Application November,

, 1944,` serial Np. r563.5287

In Grcatritain October 15, 1,942

2 claims. (C1. 121-38) `This invention relates to the governing meansemployed for automatically controlling the` output of avariable-delivery fuel pump used in conjunction with prime movers, thegoverning means being responsive to variable fluid pressure conditions.VIn particular the invention relates to a governing means consisting of aspring loaded piston or diaphragm adapted to actuate the outputcontrolling means of the pump, the piston or diaphragm being containedin a chamber. The piston (which term will hereafter be used as includingalso a diaphragm) is subject on both sides to the action of fluidpressure. Means are provided for effecting an unrestricted pressurefluidsupply to one side of the piston, and Lthis fluid can also gain accessto the other side through a restricted passage s o thatpressuredifferences can occur temporarily for actuating the piston, thepressures at the two sides being equal during a steady pressurecondition in the system. At the side of the chamber opposite to thatwhich receives the unrestricted fluid supply there is provided a releaseValve which is responsive to any predetermined condition associated withthe system, such as the speed of the pump. Govern-Y ing means as abovedescribed are hereinafter referred to as of the kind specified.

The above described governing means possesses the disadvantages thatundesired pressure or volume fluctuations may be set 11p in the liquiddelivered by the pump, and the object of the present invention is toenable this condition to be minimised in a simple and satisfactorymanner.

The invention comprises the combination with a governing means as abovedescribed, of a variableevolume chamber arranged in communication withthe valve-controlled side of the piston chamber, the Variable-volumechamber being such that it permits movement of the piston in response toa pressure change independently of the valve.

In the accompanying sheet of explanatory drawings:

Figure 1 is a diagrammatic sectional elevation of a liquid fuel pumpembodying the invention.

Figure 2 is a fragmentary sectional side View illustrating a modifiedform of the invention.

The liquid fuel pump shown in the drawing comprises a rotary body part aarranged in a casing b and having formed around its axis a plurality ofbores as c in each of which is arranged a reciprocatory plungerv d. Thebody part a is adapted to be driven in any convenient manner by theprime mover to be supplied with liquid fuel from the pump. Duringrotation of the body par-t a the plungers d are moved in one directionby an angularly movable swash plate e and thopposite direction bysprings as f, the latter being situated in the bores c, and serving tohold an end falce of the body part in contact with aflat seating g` inthe casing b. The swash plate e is of annularform and is pivoted atdiametrical- 1y opposite positions to the casing b. The seating disiorme'dwith a port h communicating With a liquid inlet i inthe casingb and with another y port y' communicating with a liquid outlet k: in

the @eine The body part a is adapted to serve also as acentriiugal'pump, and for this purpose is formed with an axial bore mwhich at one end communi- Cates with the inlet i through another port nin the Seating y, and at the other end communicates with a 'plurality ofradial passages as o in the body part."`Liqi1id from the inlet i llowsthrough thebore mand is expelled by centrifugal action through theradial passages o into the interior of the pump casing b around the bodypart a.

In one end of the casing b is formed a cylindrical chamber phavingclosed ends. Within the chamber p is arranged a piston q loaded by aspring r, and extending from one side of this piston and through a borein the casing b. at the inner end of the chamber is a rod s connected tothe swash plate e. Instead of the piston a diaphragm may be employed,and as already stated I desire this alternative to be included in theterni piston. The inner portion ofy the chamber p, that is the portionat the piston rod side of the piston q, is 'n in'free communication withthe outlet lc through a passage l in the casing b, and this portion 0fthe chamber also communicates with the other or outer portion of thechamber (which contains the spring 1) through a restricted passage t.The cluter end of the chamber p is provided With a ventru which at itsouter end forms a seating for a Valve u, this latter being responsive toany predetermined condition associated with the system.

`In the `example shown the valve 1f is formed or secured on one end'of alever w, the latterbeing pivoted` at a positiontbetween its ends on theouter end of the chamber p, and being loaded by a spring :v which tendsto hold the valve on its seating. The lever w is contained in a chambery formed on or securedto the adjacent end of the casing'b, fand'thischamber communicates with the pump inlet i. The outer side of thechamber y is bounded by a controlling diaphragm z having `-at its centrean abutment 2 which is adapted to bear on the end of the lever w remotefrom the valve o. At the outer side of and bounded in part by thediaphragm z is another chamber 3, this latter being in communicationwith the above mentioned centrifugal pump through a passage l in thecasing b. Also the diaphragm z is loaded by a spring 5 connected to anadjusting member 6, the latter being operable in any convenient mannerby an attendant to vary the effect of the Sprlng.

Assuming the swash plate e to be in a position of maximum obliquity,that isto say the position in which the pump gives its maximum output,the swash plate will remain'in this position s0 long as the pressure inthe chamber 3 (and thus acting on the controlling diaphragm a) is belowsome predetermined amount. In this condition the valve v is in itsclosed position and the liquid Likewise, if a pressure fall occurs at asufficient rate liquid flows from the chamber 9 to the chamber p underthe action of the spring loaded piston l0, and subsequently returnseither in response to a pressure rise or to pressure liquid supplied tothe end of the chamber p communicating with the chamber 9.

In the example shown in Figure 2, the passage l interconnecting thechambers p and 9 is controlled by a spring loaded Valve I2 which permitsfreeV flow of liquid from the chamber p to the chamber 9 but restrictsthe return ow. In other respects this example is similar to that shownin IFigure 1 with the exception that the restriction in the passage tinterconnecting the ends of the chamber p is effected by a plug I3,suihcient v. clearance being provided between the plug and pressures atthe two sides of the piston q are equal. But when the pressure acting onthe diaphragm e exceeds the predetermined amount the diaphragm will movethe valve v 01T its seating. The-liquid pressure in the outer portion ofthe piston chamber p will now fall and the piston q will be moved by thefluid pressure in the inner portion of the cylinder against the actionof the spring r, so moving the swash plate e in the direction forreducing the pump output until a new condition of equilibrium isreached. If the valve o subsequently moves on to its seating as a resultof the pressure on the diaphragm z falling below the predeterminedamount, the liquid pressures at the two sides of the piston q againbecome equal, and the spring then serves to move the piston in thedirection for increasing the pump output.

From the foregoing it Will be seen that as the position of the swashplate e is dependent on the pressure of the liquid in the chamber 3 andas this pressure is dependent on the speed of the pump, the latter isgoverned by the speed of the prime mover which drives the pump.

In carrying the invention into effect as shown in Figure 1, I connectthe valve-controlled outer end of the chamber p by means of a passage 'lto One end of a small variable-volume chamber 9 containing a springloaded piston I0 which controls the volume of the latter chamber, theother end of this chamber being in communication with the outeratmosphere through a vent Il. Under a steady condition in the system thepiston q of the governing means remains at rest. But when a variation(rise or fall) of iiuid pressure occurs at a sucient rate the piston qcan move in the appropriate direction in immediate response to thechange and independently of consequential movement of the valve v, asliquid can now iiow between the chamber p of the governing means and theadditional chamber 9 of variable volume. This liquid flow permitsmovement of the piston q of the governing means in response to pressureuctuations which are too brief to permit movement of this piston underthe control of the valve o. It will be understood that when a pressurerise occurs at a suicient rate liquid flows from the chamber p to thechamber 9, this being permitted by movement of the piston l0 against theaction of its spring loading, and if this pressure rise persists thevalve v will be moved away from its seating, allowing return flow ofliquid from the chamber 9 to the chamber p.

passage to allow a restricted flow of liquid through the passage.

By this invention the above mentioned disadvantage of the earlier formof governing means is effectively avoided.

This invention is not, however, limited to the particular examplesdescribed as constructional details may be varied to suit differentrequirements. Thus instead of the piston-controlled variable-volumechamber above described I may employ a chamber provided with a diaphragmand this may be loaded either by a spring or by gas under pressure; or Imay employ an extensible closed chamber constructed from flexiblematerial, for example, corrugated sheet metal.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is: Y

1. Governing means of the kind specified, having in combination a fluidpressure responsive member, a main chamber containing said member, apassage for admitting an unrestricted supply of pressure fluid to saidmain chamber at one side of said member, a restricted passage foradmitting pressure fluid to said main chamber at theother side of saidmember, a pressure-duid release valve situated at the side of said mainchamber to vwhich pressure iiuid is admitted through said restrictedpassage, and a variablevolume chamber arranged in communication with therelease valve side of said main chamber to permit movement of saidmember in response to a pressure change independently of said valve.

2. Governing means of the kind specified, having in combination a fluidpressure responsive member, a main chamber containing said member, apassage for admitting an unrestricted supply of pressure Huid to saidmain chamber at one side of said member, a restricted passage foradmitting pressure fluid to said main chamber at the other side of saidmember, a pressure-fluid release valve situated at the side of saidchamber to which pressure fluid is admitted through said restrictedpassage, a variable-volume chamber arranged in communication with therelease valve side of said main chamber to permit movement of saidmember in response to a pressure change independently of said valve, anda second valve arranged between said main chamber and saidvariable-volume chamber, said second valve serving to permit free iloWof liquid from said main chamber to said variable-volume chamber, but torestrict iiow in the opposite direction.

RICHARD JOSEPH IFIELD.

